Production of portland cement.



UNITED STATES PATENT OFFICE.

JO SEPH W. RICHARDS, OF SOUTH BETHLEHEM, AND WALTER S. LANDIS, OF BETHLEHEM, PENNSYLVANIA.

PRODUCTION OF PORTLAND CEMENT.

No Drawing.

To all whom it may concern:

Be it known that we, JOSEPH W. RIGH- ARDS, a subject of the King of Great Britain, residing at South Bethlehem, county of Northampton, State of Pennsylvania, and WALTER S. LANDIS, a citizen of the United States, residing at Bethlehem, county of -Northampton, State of Pennsylvania, have invented certain new and useful Improvements in the Production of Portland Ce ment; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present method of manufacturing Portland cement is to grind very finely, usually to 100 mesh and sometimes to 200 mesh, the raw materials entering into the composition of the cement. These raw materials are usually an argillaceous limestone (called cemenhrock) and limestone, or clay and limestone, or marl and limestone, or the usual iron blast-furnace slag and limestone. In every case, it is the invariable practice in making Portland cement to grind these raw materials very fine, as indicated, for the purpose of insuring a homogeneous mixture of the ingredients and a consequent homogeneous fritted product. IVith this present system of manufacture, in which the product is merely fritted or sintered or clinkered, the homogeneity of the product is abso lutely dependent upon the preliminary fine grinding and thorough mechanical mixing of the raw material used. In this ordinary system of manufacture, during the sintering or clinkering operation, usually performed in rotating cylindrical kilns, the constituents of the finely powdered charge combine to produce the material known as cement clinker, which when subseqtientlyyery finely ground has'the characteristic setting prop erties of Portland cement. This operation is carried 'on at a temperature which softens the mixture to such a degree that, in combination with the rotating motion of 'the kiln, a. balling effect (like the rolling or wet snow into snowballs) takes place, and the material issues in small nodular lumps known as cement clinker.

" In the ordinary operation thus described,

U terials isefiected bythe fine state of division caused by the preliminary grinding of Specification of Letters Patent.

Application filed February 28, 1911.

Patented Sept 23, 1 913.

Serial n 611,328.

the same, together with the temperature which is just sutlicient to make the mixture tated.

In the system of manufacturing Portland cement which we have devised, the raw materials do not need to be finely ground, but may be and preferably are used in the natural non-pulverized condition, although they may be broken or sized into any convcnient form. \Ve thus dispense altogether with the necessary preliminary fine grinding characteristic of the present methods of manufacture. In order to make Portland cement from these raw materials, we charge them into a furnace, preferably a shaft furnace and heat them therein by the combustion of fuel, or by the application of electrical energy, or both, to a temperature sufficient to entirely melt them together, pro

ducing a fusion thereof, sufficiently liquid to enable the product to be run from the furnace either continuously, or, if more com vcnient, to be tapped intermittently from the furnace. This liquidity is the agency upon which we rely to effect the complete and intimate mixture of all the cement forming materials of the charge into a homogeneous product. This product is preferably granulated as it runs from the furnace, as, for instance, by running it into a stream of water, or passing it before a steam or air nozzle. The granulated material when dry and sufficiently cool, is then very finely ground to the fineness requisite to develop therein the characteristic setting properties of Portland cement. \Ve recommend thatthis grinding be carried to the point where about 85% of the product will pass through a 200 mesh sieve. During the grinding any additions of gypsum or other material usual to add in the final grinding of cement clinker, may be made.

Portland cement is also made at present from ordinary blast furnace slag and limestone as raw materials, as already indi-.

- maybe ground. When used as one of the constituents for manufacturing Portland cement the blast furnace slag is. very finely ground in admixture with the neces- Sexy amount of limestone, and the well- 11 mixed materials are put through a sintering or clinkering process, usually in rotatin'g cement burmng kilns. The clinker thus obtained has'the chemical composition of Portland cement clinker and, on being finely ground, develops the setting properties of Portland cements. In this operation, the

' blast "furnace slag is practicall the equivalent of thenatural cement roc vas previously described.

used in the ordinary manufacture of Portland cements In conformity with the principles of our invention, instead of' finely grinding these raw matef rials (for instance, blast furnace slag and limestone), mixing them and then clinkering the mixture, as is at present done,

we charge into the blast furnace itself the necessary proportion of limestone hereto- 1 fore used for subsequent admixture with the blast furnace slag. We therefore produce at once a slaglike product having the desired composition of Portland cement clinker. This. liquid product is then preferably granulated, and ground very fine as before described. Such material is far more highly basic than is the slag pro? duced in the normal running of the blast furnace, and, since its composition corresponds not to blast furnace slag but to Portland cement clinker, it is capable, when finely enough ground, of develo ing the characteristic setting properties of ortland cement.

- It will of course, be understood that the purpose of grinding the liquefied and subsequently solidified slaglike material is to taining our improved product as an incident to the reduction of the ore; or the blast furnace, the electric furnace, or any other suitable 'formof furnace may be used for the sole urpose of producing our liquefied cementorming material. 1 In those instances where the heat necessary 'for the liquefaction of the raw materials is produced by. the combustion of fuel, the fuel may, according to the type of furnace used, be either admixed with the raw materials so as to constitute a portion of the charge,

or the fuel may be. carried with the air used, in the form of pulverized coal, or oil or the like, but always under conditions The composition of the cement-forming that will result in. the complete liquefaction of the raw materials, as hereinbeforei f lllly indicated. i

material thus produced by us in the liquid and afterward solidified condition, corresponds to the composition of Portland ce-' ment clinker as it is understood in the industry, viz: a composition of lime', alumina and silica asits essential constituents, the lime predominating. 5

Having thus described our invention, what we claim is: v

The process of making iron. and .Pdrtland I cement in a single furnace operation, which consists in making up the charge of ore in an iron-ore reduction furnace, having a basic lining with the raw materials for pro= ducing a lime aluminapsilicate slag and with excess of limestone sufiicient to produce a liquid product having the percentage composition of Portland cement clinker, and generating in said furnace a sufficient tem' perature to reduce .the ore and to cause the clinker to flow from the furnace in the liquid state; substantially as described.

In testimony whereof we afiix our signs. tures, in presence of two witnesses.

JOSEPH W. RICHARDS. WALTER S. LANDIS. Witnesses: v

HELEN Gr. Hu'rii, JDANmL FRIEBELY. 

